A method of fabricating an apparatus including a sealed cavity and an apparatus embodying the method are disclosed. The heat generation system includes a heating source in contact with a pole of the electrical generator rotor to heat the pole, thereby reducing heat loss from the adhesive to the pole. An exhaust venting device for purification processes is also disclosed, which allows exhaust to be vented from the top of the reactor chamber, thereby avoiding backflow of exhaust into the silicon melt and erosion of the reactor. The flange is adapted to receive at the first end a tapered bushing of increasing diameter and dimensioned such that, upon insertion of the bushing within the body a given length, the bushing frictionally engages with the inner wall surface of reducing diameter for retention therein. The compare unit performs an analysis such as a \u201cclosest neighbor\u201d analysis to determine the location of the user at the time of day closest to that of the present call.